This present invention relates generally to cannulae and associated methods. More specifically, this disclosure discusses a cannula or needle having a flashback notch that is configured to bypass a septum of an intravascular device without incurring septum damage, preventing proper retraction and shielding of the needle, and/or providing a disconcerting feel to the clinician. Further, the disclosure discusses methods for aligning various features of the needle and the septum to minimize and/or prevent damage to the septum.
Generally, vascular access devices are used for communicating fluid with the vascular system of patients. For example, catheters are used for infusing fluid (e.g., saline solution, medicaments, and/or total parenteral nutrition) into a patient, withdrawing fluids (e.g., blood) from a patient, and/or monitoring various parameters of the patient's vascular system.
Intravenous (IV) catheter assemblies are among the various types of intravascular access devices. Over-the-needle peripheral IV catheters are a common IV catheter configuration. As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. The introducer needle is generally a venipuncture needle coupled to a needle assembly that helps guide the needle and facilitates its cooperation with the catheter. At least the inner surface of the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and, thereby, to facilitate insertion of the catheter into the blood vessel. The catheter and the introducer needle are often assembled so that the sharp distal tip of the introducer needle extends beyond the distal tip of the catheter. Moreover, the catheter and needle are often assembled so that during insertion, the bevel of the needle faces up, away from the patient's skin. The catheter and introducer needle are generally inserted at a shallow angle through the patient's skin into a blood vessel.
In order to verify proper placement of the needle and/or the catheter in the blood vessel, the operator generally confirms that there is a “flashback” of blood into a flashback chamber associated with the needle assembly. Flashback generally entails the appearance of a small amount of blood, which exits the needle through an aperture or notch which is visible within the needle assembly or between the needle and the transparent catheter.
The operator may then withdraw the introducer needle from the catheter. In some cases, the intravascular device further includes an internal septum having a slit or opening through which the introducer needle passes. The septum generally provides a fluid tight seal around a cross-section of the introducer needle. The septum is positioned within the intravascular device so as to provide a fluid barrier that prevents undesirable exposure to blood during and after the catheterization process. Following insertion of the cannula or catheter, the introducer needle is withdrawn from the intravascular device, whereby the “flashback” aperture or notch must pass through the slit in the septum. As the notch is typically provided by removing a portion of the needle's wall, the septum can engage or snag on a distal edge of the notch as the introducer needle is retracted past the septum. This engagement can prevent proper retraction and shielding of the needle, be disconcerting to the clinician, or even damage the septum.
Thus, while methods currently exist for incorporating a septum into an intravascular device having flashback capability, challenges still exist. Accordingly, it would be an improvement in the art to augment or even replace current techniques with other techniques.